The present invention relates to cleaning filters of wet/dry vacuum cleaners, and preventing clogging thereto.
Single-stage wet/dry vacuum cleaners, known in the trade as xe2x80x9cSHOP VACS(copyright)xe2x80x9d have evolved into a fairly standard design including a removable power head atop a debris collection drum. A cylindrical pleated-paper disposable filter is fitted onto a perforated cylindrical tube, which is the air intake of a motor driven impeller housing. Typically, this tube is axially aligned with the impeller motor shaft. These high powered vacuum cleaners are quite efficient and can handle a wide variety of dust and debris types commonly encountered on a shop or industrial plant floor, or on a construction or remodelling site.
When handling certain types of large low-density particles or tufts, however, the filter gets clogged often with agglomerations of debris on the outer surface of the filter. This reduces air flow and impedes the effectiveness of the wet/dry vacuum cleaner (SHOP VAC(copyright)) necessitating frequent manual cleaning of the surface of the filter or its replacement with a new one. Debris from fiberglass insulation, fabric handling, and sawdust are common culprits. In the case of some softwood sawdust, the vacuum induced agglomerate on the filter surface is actually an agglutinate mediated by the resins in the wood.
It is therefore an object of the present invention to provide a filter for a wet/dry vacuum cleaner (SHOP VAC(copyright)) which does not clog easily.
It is yet another object of the present invention to provide a wet/dry vacuum cleaner (SHOP VAC(copyright)) filter, which is cleaned during rotating use.
It is yet another object of the present invention to clean a wet/dry vacuum cleaner (SHOP VAC(copyright)) filter during use, without damaging the filter.
It is a further object to improve over the disadvantages of the prior art.
In keeping with these objects and others which may become apparent, the present invention includes a self cleaning rotating filter for a wet/dry vacuum cleaner (such as, but not limited to those sold under the tradename SHOP VAC(copyright)).
The rotating filter feature of this invention addresses the problem of rapid surface contamination and clogging of the filter surface by certain types of debris. The outward appearance and general internal operation of the wet/dry vacuum cleaner (SHOP VAC(copyright)) is retained, however, the filter is now rotated past a stationary elastomeric blade or brush with stiff bristles which mechanically removes the majority of the surface globs automatically thereby lengthening the service interval for effective operation. Most of the debris removed by the blade or brush simply falls down into the debris collection drum in a denser larger glob.
In the first embodiment, the impeller driving shaft of the motor is extended through the perforated tube concentric with the filter so that it drives a speed reduction gearbox at its distal end, which, in turn, rotates the filter at a slow speed. Direct drive at impeller speed would tend to subject the filter to stresses, which would tend to make it billow and cause undue friction against the elastomeric blade or brush. Also, this high speed rotation of the filter would interfere with the normal desired air flow.
In the preferred embodiment, the filter is rotated at a more desirable very low speed of the order of 10 revolutions per minute. Although difficult or expensive to achieve through mechanical reduction of the speed of the impeller motor; this is a simple application of a separate timing gearmotor. This embodiment also precludes the need to extend the impeller motor shaft. The latter has the undesirable propensity for unbalancing the impeller motor and thereby introducing vibration. Alternate methods of coupling the impeller motor to a gearbox complicate the air flow geometry or introduce other mechanical complications such as belt or external gear drives in a dusty environment.